Characterisation of a catalase-negative methicillin-resistant Staphylococcus aureus isolate from a dog

A catalase-negative MRSA strain and a methicillin resistant Staphylococcus pseudintermedius strain (MRSP) were isolated from a dog affected by a severe form of pododermatitis. The catalase negative isolate was typed as SCCmec I, PVL negative, ST5 t002 strain. A deletion at position 487 of the kat gene altered the functionality of the catalase enzyme. This is the first report of a catalase-negative MRSA in animals. As catalase test is a rapid assay routinely employed for the identification of staphylococci in clinical microbiology laboratories, the presence of MRSA with this uncommon phenotype may be underestimated. Moreover, catalase-negative staphylococci should be investigated more in-depth in order to assess their virulence.